I have heard that Schiff's base only gives a positive test for aldehydes. Glucose is an aldehyde. However, I was told that glucose doesn't give a positive Schiff's base test. Is this correct? If so, how?
Schiff test is a colorimetric method for determination of aldehyde groups. Both glucose and fructose are monosaccharides and exhibit oxo-cyclo tautomerism. Glucose is an aldose and has aldehyde group in linear form. Whereas fructose is a ketose and doesn't give a positive Schiff test.